The Barry Railway Company was born to release the stranglehold of the Taff Vale Railway and Cardiff Docks on the export of South Wales’ coal. Work on it started in 1885 and thanks to their efficiency, by 1910, Barry Docks had overtaken their near neighbour in terms of tonnage shifted.

Within four years, the company had built a substantial rail network including several branches and an 18½-mile main line from Trehafod into the docks. Included in this was a double-track bore of 1,868 yards at Wenvoe which first saw active service in 1889.

The tunnel is brick lined except for a short section at its southern end where a change in geology occurs. Towards its centre is a single ventilation shaft, also brick lined and almost the full width of the structure.

Traffic through the tunnel came to a premature close on 31st March 1963 thanks to a fire which destroyed Tynycaeau North signal box. Since then, it has become home to a large water main and extraordinary mineral deposits which adorn the walls. A pile of junk has come to rest at the foot of the shaft and the tunnel now suffers badly from flooding, with waters reaching a depth of four feet after heavy rainfall.